Stream sediments in Pennsylvania downstream from two fracking wastewater treatment facilities were found to contain radioactive material and carcinogens, according to study scientists from Penn State, Colorado State and Dartmouth universities.

The study’s findings, published Thursday, came after Penn State’s Bill Burgos and his fellow scientists sought to discover what had been the effect of the strategy of treating and releasing fracking wastewater, according to the Independent.

They sampled sediments and groundwater from the Conemaugh River water, downstream from two facilities that were created to make the water used in the fracking process fit for release into the environment.